Power converter

ABSTRACT

A power converter can include: first and second terminals; N A-type switching power stage circuits, each having a first energy storage element, where N is a positive integer, a first terminal of a first A-type switching power stage circuit in the N A-type switching power stage circuits is coupled to the first terminal of the power converter, and a second terminal of each of the N A-type switching power stage circuits is coupled to the second terminal of the power converter; one B-type switching power stage circuit; and N second energy storage elements, each being coupled to one of the N A-type switching power stage circuits, and the B-type switching power stage circuit is coupled between a terminal of one of the N second energy storage elements corresponding to the B-type switching power stage circuit and the second terminal of the power converter.

RELATED APPLICATIONS

This application claims the benefit of Chinese Patent Application No.201810612057.5, filed on Jun. 14, 2018, which is incorporated herein byreference in its entirety.

FIELD OF THE INVENTION

The present invention generally relates to the field of powerelectronics, and more particularly to power converters.

BACKGROUND

A switched-mode power supply (SMPS), or a “switching” power supply, caninclude a power stage circuit and a control circuit. When there is aninput voltage, the control circuit can consider internal parameters andexternal load changes, and may regulate the on/off times of the switchsystem in the power stage circuit. Switching power supplies have a widevariety of applications in modern electronics. For example, switchingpower supplies can be used to drive light-emitting diode (LED) loads.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic block diagram of a first example power converter,in accordance with embodiments of the present invention.

FIG. 2 is a waveform diagram of example operation of the first examplepower converter, in accordance with embodiments of the presentinvention.

FIG. 3 is another waveform diagram of example operation of the firstexample power converter, in accordance with embodiments of the presentinvention.

FIG. 4 is a schematic block diagram of a second example power converter,in accordance with embodiments of the present invention.

FIG. 5 is a waveform diagram of example operation of the second examplepower converter, in accordance with embodiments of the presentinvention.

FIG. 6 is a schematic block diagram of a third example power converter,in accordance with embodiments of the present invention.

FIG. 7 is a schematic block diagram of a fourth example power converter,in accordance with embodiments of the present invention.

FIG. 8 is a schematic block diagram of a fifth example power converter,in accordance with embodiments of the present invention.

FIG. 9 is a schematic block diagram of a sixth example power converter,in accordance with embodiments of the present invention.

DETAILED DESCRIPTION

Reference may now be made in detail to particular embodiments of theinvention, examples of which are illustrated in the accompanyingdrawings. While the invention may be described in conjunction with thepreferred embodiments, it may be understood that they are not intendedto limit the invention to these embodiments. On the contrary, theinvention is intended to cover alternatives, modifications andequivalents that may be included within the spirit and scope of theinvention as defined by the appended claims. Furthermore, in thefollowing detailed description of the present invention, numerousspecific details are set forth in order to provide a thoroughunderstanding of the present invention. However, it may be readilyapparent to one skilled in the art that the present invention may bepracticed without these specific details. In other instances, well-knownmethods, procedures, processes, components, structures, and circuitshave not been described in detail so as not to unnecessarily obscureaspects of the present invention.

Power electronic technology is rapidly being developed to help addressenergy shortage problems, and in particular a power converter having ahigh gain is an important element. In some approaches, a cascadeconnection may be utilized to achieve a high gain of the powerconverter. However, such an approach may result in a relatively largeripple of an output voltage, and can require a relatively large outputcapacitance.

In one embodiment, a power converter can include: (i) a first terminal;(ii) a second terminal; (iii) N A-type switching power stage circuits,each having a first energy storage element, where N is a positiveinteger, a first terminal of a first A-type switching power stagecircuit in the N A-type switching power stage circuits is coupled to thefirst terminal of the power converter, and a second terminal of each ofthe N A-type switching power stage circuits is coupled to the secondterminal of the power converter; (iv) one B-type switching power stagecircuit; and (v) N second energy storage elements, where each of the Nsecond energy storage elements is coupled to one of the N A-typeswitching power stage circuits, and the B-type switching power stagecircuit is coupled between a terminal of one of the N second energystorage elements corresponding to the B-type switching power stagecircuit and the second terminal of the power converter.

Referring now to FIG. 1, shown is a schematic block diagram of a firstexample power converter, in accordance with embodiments of the presentinvention. In this particular example, the power converter can includeA-type switching power stage circuit 11, B-type switching power stagecircuit 12, terminal “a,” terminal “c,” energy storage element Ci1,transistor Q1, and output capacitor Co. In this particular example,terminal a may be configured as an input terminal of the power converterto receive input voltage Vin, and terminal c may be configured as anoutput terminal of the power converter to generate output voltage Vout.

A first terminal of A-type switching power stage circuit 11 can connectto terminal a, and a second terminal of A-type switching power stagecircuit 11 can connect to terminal c. A-type switching power stagecircuit 11 can include transistor Q2, transistor Q3, energy storageelement Cf1, and magnetic element Lo1. Transistor Q2 can connect betweenterminals a and e. Energy storage element Cf1 can connect betweenterminals e and f. Magnetic element Lo1 can connect between terminals fand c. Transistor Q3 can connect between terminal f and a groundterminal. Terminal e is a common node between transistor Q2 and energystorage element Cf1. Terminal f is a common node between energy storageelement Cf1 and magnetic element Lo1.

Energy storage element Ci1 can connect to A-type switching power stagecircuit 11. Terminal “g” of energy storage element Ci1 can connect toterminal e via transistor Q1 connected in series with energy storageelement Ci1, and the other terminal of energy storage element Ci1 canconnect to the ground terminal. B-type switching power stage circuit 12can connect between terminal g of energy storage element Ci1 andterminal c. B-type switching power stage circuit 12 can includetransistors Q4 and Q5, and magnetic element Lo2. Transistors Q4 and Q5can connect between terminal g and the ground terminal. Magnetic elementLo2 can connect between terminals h and c. Terminal h is a common nodebetween transistors Q4 and Q5.

For example, each of transistors Q3 and Q5 is a rectification switch(e.g., a metal-oxide-semiconductor field-effect transistor [MOSFET], abipolar junction transistor [BJT], and an insulated gate bipolartransistor [IGBT], etc.). In another example, each of transistors Q3 andQ5 may be replaced with a diode. Further, energy storage parameters ofenergy storage elements Cf1 and Ci1 can be set to control A-typeswitching power stage circuit 11 to meet inductor volt-second balance(e.g., to control magnetic element Lo1 to be in a stable state). Thatis, the amount of change in a current of magnetic element Lo1 during aswitching period may be controlled to be approximately zero.

Referring now to FIG. 2, shown is a waveform diagram of exampleoperation of the first example power converter, in accordance withembodiments of the present invention. In this particular example, thepower converter can perform in-phase control on operation states ofA-type switching power stage circuit 11 and B-type switching power stagecircuit 12. Under the in-phase control, transistor Q2 may have a sameswitching state as transistor Q4, and transistor Q3 may have a sameswitching state as transistor Q5, where the switching state oftransistor Q2 is complementary to the switching state of transistor Q3.Also, switching control signal GH1 for transistor Q2 may be the same asswitching control signal GH2 for transistor Q4 (e.g., transistors Q2 andQ4 have the same switching state and the same duty cycle). Switchingcontrol signal GL1 for transistor Q3 may be the same as switchingcontrol signal GL2 for transistor Q5. Switching control signal GH1 fortransistor Q2 may be complementary to switching control signal GL1 fortransistor Q3. Switching control signal GH2 for transistor Q4 may becomplementary to the switching control signal GL2 for transistor Q5.Switching control signal GL1′ for transistor Q1 may be the same asswitching control signal GL1 for transistor Q3. In this case, the powerconverter can adjust the duty cycle of transistor Q2, in order to adjustoutput voltage Vout and keep stabilization of output voltage Vout.

The example power converter may have two states during a switchingperiod. In a time period from t0 to t1, switching control signal GH1 fortransistor Q2 and switching control signal GH2 for transistor Q4 can beat a high level. In this case, transistors Q2 and Q4 may be turned on,and transistors Q1, Q3, and Q5 turned off. Energy storage element Cf1may store energy, and the current of magnetic element Lo1 can graduallybe increased. Energy storage element Ci1, as a power supply, may supplypower to a load via B-type switching power stage circuit 12. A currentof magnetic element Lo2 may gradually be increased. In a time periodfrom t1 to t2, switching control signal GH1 for transistor Q2 andswitching control signal GH2 for transistor Q4 can be low. In this case,transistors Q2 and Q4 may be turned off, and transistors Q1, Q3, and Q5can be turned on. The current of magnetic element Lo1 and the current ofmagnetic element Lo2 may gradually be decreased. Energy storage elementCf1, as a power supply, can charge energy storage element Ci1, andenergy storage element Ci1 can store energy. Based on characteristics ofthe inductor volt-second balance of the A-type switching power stagecircuit and the B-type switching power stage circuit, the followingrelationships may be obtained in formulas (1) and (2).

(Vin−Vcf1)*D=Vout  (1)

Vci1*D=Vout  (2)

Here, Vin represents an input voltage, Vcf1 represents a voltage acrossenergy storage element Cf1, D represents a duty cycle (e.g., a ratio ofa conduction time of transistor Q2 to the switching period) oftransistor Q2, Vci1 represents a voltage across energy storage elementCi1, and Vout represents an output voltage. It can be seen from FIG. 1that when switching control signals GL1 and GL1′ are at a high level,energy storage element Cf1 may effectively be coupled in parallel withenergy storage element Ci1. Thus, the voltage across energy storageelement Cf1 may be equal to the voltage across energy storage elementCi1 (e.g., Vcf1=Vci1). Therefore, a relationship between the inputvoltage and the output voltage of the power converter In this particularexample may be expressed as the following formula (3).

$\begin{matrix}{\frac{Vout}{Vin} = \frac{D}{2}} & (3)\end{matrix}$

In this particular example, due to the interleaving connection and thein-phase control, the power converter may have relatively a high gainand an adjustable stabilized output voltage, and with relatively simplecontrol.

Referring now to FIG. 3, shown is another waveform diagram of exampleoperation of the first example power converter, in accordance withembodiments of the present invention. In this particular example, thepower converter can perform phase-shift control on operation states ofA-type switching power stage circuit 11 and B-type switching power stagecircuit 12. Under the phase-shift control, conduction timings oftransistors Q2 and Q4 have a phase difference α (e.g., 180°). Aswitching state of transistor Q2 may be complementary to a switchingstate of transistor Q3. A switching state of transistor Q4 may becomplementary to a switching state of transistor Q5. A switching stateof transistor Q1 may be the same as the switching state of transistorQ3. Transistors Q2 and Q4 may have a same duty cycle D. In this case,the power converter can adjust duty cycle D (e.g., D<0.5) to adjustoutput voltage Vout and keep stabilization of output voltage Vout.

In a time period from t3 to t4, switching control signals GH1 and GL2may be at a high level. In this case, transistors Q2 and Q5 can beturned on, and transistors Q1, Q3, and Q4 may be turned off. Current I1of magnetic element Lo1 may be increased, and current I2 of magneticelement Lo2 can be decreased. In a time period from t4 to t5, switchingcontrol signals GL1, GL1′, and GL2 may be at a high level. In this case,transistors Q1, Q3, and Q5 may be turned on, and transistors Q2 and Q4can be turned off. Current I1 of magnetic element Lo1 may be decreased,and current I2 of magnetic element Lo2 can be decreased. In a timeperiod from t5 to t6, switching control signals GL1, GL1′, and GH2 maybe at a high level. In this case, transistors Q1, Q3, and Q4 can beturned on, and transistors Q2 and Q5 may be turned off. Current I1 ofmagnetic element Lo1 may be decreased, and current I2 of magneticelement Lo2 can be increased.

In a time period from t6 to t7, switching control signals GL1, GL1′, andGL2 can be at a high level. In this case, transistors Q1, Q3, and Q5 maybe turned on, and transistors Q2 and Q4 can be turned off. Current I1 ofmagnetic element Lo1 may be decreased, and current I2 of magneticelement Lo2 can be decreased. In particular embodiments, due to theinterleaving connection and the phase-shift control, the ripple of theoutput voltage can be reduced, and the required output capacitance canalso be reduced. Based on characteristics of the inductor volt-secondbalance of the A-type switching power stage circuit and the B-typeswitching power stage circuit, the following relationships may beobtained in formulas (4) and (5).

(Vin−Vcf1)*1)=Vout  (4)

Vci1*D=Vout  (5)

Here, Vin represents an input voltage, Vcf1 represents a voltage acrossenergy storage element Cf1, D represents a duty cycle (e.g., a ratio ofa conduction time of transistor Q2 to the switching period) oftransistor Q2, Vci1 represents a voltage across energy storage elementCi1, and Vout represents an output voltage. It can be seen from FIG. 1that when switching control signals GL1 and GL1′ are at a high level,energy storage element Cf1 can effectively be coupled in parallel toenergy storage element Ci1. Thus, the voltage across energy storageelement Cf1 may be equal to the voltage across energy storage elementCi1 (e.g., Vcf1=Vci1). Therefore, a relationship between the inputvoltage and the output voltage of the power converter may be expressedas the following formula (6).

$\begin{matrix}{\frac{Vout}{Vin} = \frac{D}{2}} & (6)\end{matrix}$

In this particular example, due to the interleaving connection and thephase-shift control, the ripple of the output voltage can be reduced,and the required output capacitance of output capacitor Co can also bereduced. Further, the power converter may have a relatively high gainand an adjustable stabilized output voltage.

Referring now to FIG. 4, shown is a schematic block diagram of a secondexample power converter, in accordance with embodiments of the presentinvention. In this particular example, the power converter can includeA-type switching power stage circuit 41, A-type switching power stagecircuit 42, B-type switching power stage circuit 43, terminal z,terminal m, energy storage elements Ci2 and Ci3, transistors Q11 andQ12, and output capacitor Co. In this particular example, terminal z isconfigured as an input terminal of the power converter to receive inputvoltage Vin. Terminal m is configured as an output terminal of the powerconverter to generate output voltage Vout. Energy storage element Ci2can connect to A-type switching power stage circuit 41. For example, oneterminal i1 of energy storage element Ci2 can connect to a common node“i” between transistor Q21 and energy storage element Cf2 via transistorQ11 connected in series with energy storage element Ci2, and the otherterminal of energy storage element Ci2 can connect to a ground terminal.

In this particular example, A-type switching power stage circuit 42 canconnect between one terminal of energy storage element Ci2 and terminalm (e.g., between terminals i1 and m). A-type switching power stagecircuit 42 can include transistors Q22 and Q32, energy storage elementCf3, and magnetic element L2. Transistor Q22 can connect betweenterminals it and k. Energy storage element Cf3 can connect betweenterminals k and n. Magnetic element L2 can connect between terminals nand m. Transistor Q32 can connect between terminal n and the groundterminal. Terminal k is a common node between transistor Q22 and energystorage element Cf3. Terminal n is a common node between energy storageelement Cf3 and magnetic element L2. A second terminal of A-typeswitching power stage circuit 41 and a second terminal of A-typeswitching power stage circuit 42 can connect to terminal m.

Energy storage element Ci3 can connect to A-type switching power stagecircuit 42. For example, one terminal i2 of energy storage element Ci3can connect to common node k between transistor Q22 and energy storageelement Cf3 via transistor Q12 connected in series with energy storageelement Ci3, and the other terminal of energy storage element Ci3 canconnect to the ground terminal. B-type switching power stage circuit 43can connect between terminal i2 of energy storage element Ci3 andterminal m. For example, each of transistors Q31, Q32, and Q51 is arectification switch (e.g., a MOSFET, a BJT, an IGBT, etc.). In anotherembodiment, each of transistors Q31, Q32, and Q51 may be replaced with adiode. Further, energy storage parameters of energy storage elements Cf2and Cf3, and energy storage elements Ci2 and Ci3 can be set to controlA-type switching power stage circuits 41 and 42 to meet inductorvolt-second balance (e.g., to control magnetic elements L1 and L2 to bein a stable state). That is, the amount of change in each of currents ofmagnetic elements L1 and L2 during a switching period may be controlledto be approximately zero.

For example, the power converter can perform in-phase control onoperation states of A-type switching power stage circuits 41 and 42, andB-type switching power stage circuit 43. Transistors Q21, Q22, and Q41may have a same duty cycle D and a same switching state. A switchingstate of transistor Q31 may be complementary to the switching state oftransistor Q21. Transistors Q31, Q32, Q11, Q12, and Q51 may have a sameswitching state. In this case, the power converter can adjust duty cycleD, in order to adjust output voltage Vout and keep stabilization ofoutput voltage Vout. Based on characteristics of the inductorvolt-second balance of A-type switching power stage circuits 41 and 42,and B-type switching power stage circuit 43, the following relationshipsin formulas (7), (8), and (9) may be obtained.

(Vin1−Vcf2)*D=Vout  (7)

(Vci2−Vcf3)*D=Vout  (8)

Vci3*D=Vout  (9)

Here, Vin represents an input voltage, Vcf2 represents a voltage acrossenergy storage element Cf2, D represents a duty cycle (e.g., a ratio ofa conduction time of transistor Q21 to the switching period) oftransistor Q21, Vci2 represents a voltage across energy storage elementCi2, Vcf3 represents a voltage across energy storage element Cf3, Vci3represents a voltage across energy storage element Ci3, and Voutrepresents an output voltage. It can be seen from FIG. 4 that whenswitching control signals GL3 and GL3′ are high, energy storage elementCf2 can effectively be coupled in parallel to energy storage elementCi2. When switching control signals GL4 and GL4′ are high, energystorage element Cf3 can effectively be coupled in parallel to energystorage element Ci3. Thus, the voltage across energy storage element Cf2may be equal to the voltage across energy storage element Ci2, and thevoltage across energy storage element Cf3 is equal to the voltage acrossenergy storage element Ci3 (e.g., Vcf2=Vci2 and Vcf3=Vci3). Therefore, arelationship between the input voltage and the output voltage of thepower converter may be expressed as the following formula (10).

$\begin{matrix}{\frac{Vout}{Vin} = \frac{D}{3}} & (10)\end{matrix}$

In this particular example, the power converter may have a relativelyhigh gain and an adjustable stabilized output voltage, and with arelatively simple control manner.

Referring now to FIG. 5, shown is a waveform diagram of exampleoperation of the second example power converter, in accordance withembodiments of the present invention. In this particular example, thepower converter can perform phase-shift control on operation states ofA-type switching power stage circuits 41 and 42, and B-type switchingpower stage circuit 43. Under the phase-shift control with reference toFIG. 4, conduction timings of transistors Q21, Q22, and Q41 may have asame phase difference α1 (e.g., α1 is 120°). A switching state oftransistor Q21 may be complementary to a switching state of transistorQ31, a switching state of transistor Q22 may be complementary to aswitching state of transistor Q32, and a switching state of transistorQ41 may be complementary to a switching state of transistor Q51.Switching states of transistors Q11 and Q12 may be the same with theswitching state of transistor Q31. Also, transistors Q21, Q22, andtransistor Q41 may have a same duty cycle D. In this case, the powerconverter can adjust duty cycle D (e.g., D<0.5), in order to adjustoutput voltage Vout and keep stabilization of output voltage Vout.

Switching control signals GH3, GH4, GH5, GL3, GL4, GL5, GL3′, and GL4′may respectively be used to control transistors Q21, Q22, Q41, Q31, Q32,Q51, Q11, and Q12. In a time period from t0′ to t1′, switching controlsignals GH3, GL4, GL4′, and GL5 may be at a high level. In this case,transistors Q21, Q32, Q12, and Q51 can be turned on, and transistorsQ31, Q11, Q22 and Q41 are turned off. Current IL1 of magnetic element L1may be increased, and current IL2 of magnetic element L2 and current IL3of magnetic element L3 can be decreased.

In a time period from t1′ to t2′, switching control signals GL3, GL3′,GH4, and GL5 may be at a high level. In this case, transistors Q31, Q11,Q22, and Q51 can be turned on, and transistors Q21, Q32, Q12, and Q41may be turned off. Current IL2 of magnetic element L2 may be increased,and current IL1 of magnetic element L1 and current IL3 of magneticelement L3 can be decreased. In a time period from t2′ to t3′, switchingcontrol signals GL3, GL3′, GL4, GL4′, and GH5 are at a high level. Inthis case, transistors Q31, Q11, Q32, Q12, and Q41 can be turned on, andtransistors Q21, Q22, and Q51 may be turned off. Current IL1 of magneticelement L1 and current IL2 of magnetic element L2 may be decreased, andcurrent IL3 of magnetic element L3 may be increased.

It can be seen from waveform diagrams of current IL1 of magnetic elementL1, current IL2 of magnetic element L2, and current IL3 of magneticelement L3 that, due to the interleaving connection and the phase-shiftcontrol, the ripple of the output voltage may be reduced, and therequired output capacitance can also be reduced. Based oncharacteristics of the inductor volt-second balance of A-type switchingpower stage circuits 41 and 42, and B-type switching power stage circuit43, the following relationships may be obtained in formulas (11), (12),and (13).

(Vin−Vcf2)*D=Vout  (11)

(Vci2−Vcf3)*D=Vout  (12)

Vci3*D=Vout  (13)

Here, Vin represents an input voltage, Vcf2 represents a voltage acrossenergy storage element Cf2, D represents a duty cycle (e.g., a ratio ofa conduction time of transistor Q21 to the switching period) oftransistor Q21, Vci2 represents a voltage across energy storage elementCi2, Vcf3 represents a voltage across energy storage element Cf3, Vci3represents a voltage across energy storage element Ci3, and Voutrepresents an output voltage. It can be seen from FIG. 4 that thevoltage across energy storage element Cf2 may be equal to the voltageacross energy storage element Ci2, and the voltage across energy storageelement Cf3 is equal to the voltage across the second energy storageelement Ci3 (e.g., Vcf2=Vci2 and Vcf3=Vci3). Therefore, a relationshipbetween the input voltage and the output voltage of the power convertermay be expressed as the following formula (14).

$\begin{matrix}{\frac{Vout}{Vin} = \frac{D}{3}} & (14)\end{matrix}$

In this particular example, due to the interleaving connection and thephase-shift control, the ripple of the output voltage can be reduced,and the required output capacitance of output capacitor Co can also bereduced. Further, the power converter may have a relatively high gainand an adjustable stabilized output voltage.

Referring now to FIG. 6, shown is a schematic block diagram of a thirdexample power converter, in accordance with embodiments of the presentinvention. In this particular example, the power converter can include NA-type switching power stage circuits 61-6N (e.g., N is a positiveinteger), one B-type switching power stage circuit 6 a, terminal m1,terminal o1, N energy storage elements Ci1-CiN, N transistors Q11-Q1N,and output capacitor Co. In this particular example, terminal m1 may beconfigured as an input terminal of the power converter to receive inputvoltage Vin. Terminal o1 can be configured as an output terminal of thepower converter to generate output voltage Vout.

As shown in FIG. 6, j-th energy storage element Cij can connect to j-thA-type switching power stage circuit 6 j, where j=1, 2, . . . , N. Forexample, one terminal of j-energy storage element Cij can connect toj-th A-type switching power stage circuit 6 j via transistor Q1 jconnected in series with j-th energy storage element Cij, and the otherterminal of j-th energy storage element Cij can connect to a groundterminal. For example, terminal x2 of energy storage element Ci1 canconnect to terminal x1 via transistor Q11 connected in series withenergy storage element Ci1. A first terminal of A-type switching powerstage circuit 61 can connect to the terminal m1, and a second terminalof A-type switching power stage circuit 61 can connect to terminal o1.When N>1, an n-th A-type switching power stage circuit 6 n can connectbetween an (n−1)−th energy storage element Ci(n−1) and terminal o1,where n=2, 3, . . . , N. A second terminal of each of the A-typeswitching power stage circuits can connect to terminal o1.

The j-th A-type switching power stage circuit 6 j can include transistorQ2 j, energy storage element Cfj, transistor Q3 j, and magnetic elementLj. In the case of j=1, one terminal of transistor Q21 can connect toterminal m1, and the other terminal of transistor Q21 can connect toenergy storage element Cf1. Magnetic element L1 can connect betweenenergy storage element Cf1 and terminal o1. Transistor Q31 can connectbetween the ground terminal and terminal x4, which is a common nodebetween energy storage element Cf1 and magnetic element L1. In the caseof j>1, one terminal of transistor Q2 j can connect to a common nodebetween transistor Q1(j−1) and energy storage element Ci(j−1), and theother terminal of transistor Q2 j can connect to energy storage elementCfj. Magnetic element Lj can connect between energy storage element Cfjand terminal o1. Transistor Q3 j can connect between a terminal that isa common node between energy storage element Cfj and magnetic elementLj, and the ground terminal.

B-type switching power stage circuit 6 a can connect between to terminalx3 of energy storage element CiN and terminal o1. B-type switching powerstage circuit 6 a can include transistor Q41, transistor Q51, andmagnetic element La. For example, each of transistors Q3 j and Q51 is arectification switch (e.g., an MOSFET, a BJT, and IGBT, etc). In anotherexample, each of transistors Q3 j and Q51 may be replaced with a diode.Energy storage parameters of energy storage elements Cfj and Cij may beset to control A-type switching power stage circuit 6 j to meet inductorvolt-second balance (e.g., to control the first magnetic element Lj tobe in a stable state). That is, the amount of change in a current ofmagnetic element Lj during a switching period may be controlled to beapproximately zero.

In this particular example, energy storage elements Ci1-CiN, as powersupplies, may respectively supply input voltages to the correspondingA-type switching power stage circuits 62-6N and B-type switching powerstage circuit 6 a. Energy storage element Cfj can charge energy storageelement Cij when energy storage element Cfj meets a predeterminedcondition (e.g., transistor Q1 j is turned on). In this particularexample, the BUCK topology is used in A-type switching power stagecircuits 6 j and B-type switching power stage circuit 6 a, in order toachieve a high buck ratio. It should be understood that A-type switchingpower stage circuits 6 j and B-type switching power stage circuit 6 amay be implemented by using any suitable converter topology (e.g., Boosttopology, a Buck topology, a Boost-Buck topology, a Zeta topology, aSepic topology, a Cuk topology, a flyback converter, a forwardconverter, a push-pull converter, a half-bridge converter, a full-bridgeconverter, an LLC converter, etc.) in certain embodiments.

For example, the power converter can perform in-phase control onoperation states of A-type switching power stage circuit 6 j and B-typeswitching power stage circuit 6 a. Under the in-phase control,transistors Q21-Q2N may have a same switching state as transistor Q41,and transistors Q31-Q3N may have a same switching state as transistorsQ11-Q1N, and transistor Q51, where a switching state of the transistorQ2 j may be complementary to a switching state of transistor Q3 j.Transistors Q21-Q2N and transistor Q41 may have a same duty cycle. Inthis case, the power converter can adjust the duty cycle of transistorQ21, in order to adjust the output voltage Vout and keep stabilizationof output voltage Vout. Based on characteristics of the inductorvolt-second balance of A-type switching power stage circuits 61-6N andB-type switching power stage circuit 6 a, the following relationshipsmay be obtained in formulas (15), (16), (17), and (18).

(Vin−Vcf1)*D=Vout  (15)

(Vci1−Vcf2)*D=Vout  (16)

(Vci(N−1)−VcfN)*D=Vout  (17)

VciN*D=Vout  (18)

Here, Vin represents an input voltage, Vcf1 represents a voltage acrossenergy storage element Cf1, D represents a duty cycle (e.g., a ratio ofa conduction time of transistor Q21 to the switching period) oftransistor Q21, Vci1 represents a voltage across energy storage elementCi1, Vcf2 represents a voltage across energy storage element Cf2,Vci(N−1) represents a voltage across energy storage element Ci(N−1),VciN represents a voltage across energy storage element CiN, and Voutrepresents an output voltage. It can be seen from the connectionrelationship shown in FIG. 6 that a voltage across energy storageelement Cfj may be equal to a voltage across energy storage element Cij(e.g., Vcfj=Vcij). Therefore, a relationship between the input voltageand the output voltage of the power converter may be expressed as thefollowing formula (19).

$\begin{matrix}{\frac{Vout}{Vin} = \frac{D}{N}} & (19)\end{matrix}$

In this particular example, the power converter has a relatively highgain and an adjustable stabilized output voltage, with a relativelysimple control manner. In another example, the power converter canperform phase-shift control on operation states of A-type switchingpower stage circuit 6 j and B-type switching power stage circuit 6 a.Under the phase-shift control, transistors Q21-Q2N and transistor Q41may be controlled to have a same phase difference between conductiontimings of transistors Q21-Q2N and transistor Q41. For example, thephase difference is 360°/(N+1). A switching state of transistor Q2 j maybe complementary to a switching state of transistor Q3 j, a switchingstate of transistor Q1 j may be the same as the switching state oftransistor Q3 j, and a switching state of transistor Q41 may becomplementary to a switching state of the transistor Q51. TransistorsQ21-Q2N and transistor Q41 may have a same duty cycle. In this case, thepower converter can adjust the duty cycle of transistor Q21, in order toadjust output voltage Vout and keep stabilization of output voltageVout.

It can be seen from the above current waveforms, the ripple of thecurrent may be reduced as the number of the A-type switching power stagecircuits is increased. Similarly, due to the interleaving connection andthe phase-shift control, the ripple of the output voltage can bereduced, and the required output capacitance can also be reduced. Anincreased number of the A-type switching power stage circuits maycorrespond to the low ripple of the output voltage, thereby requiring asmall output capacitance. Based on characteristics of the inductorvolt-second balance of A-type switching power stage circuits 61-6N, andB-type switching power stage circuit 6 a, the following relationships offormulas (20), (21), (22), and (23) may be obtained.

(Vin−Vcf1)*D=Vout  (20)

(Vci1−Vcf2)*D=Vout  (21)

(Vci(N−1)−VcfN)*D=Vout  (22)

VciN*D=Vout  (23)

Here, Vin represents input voltage, Vcf1 represents a voltage acrossenergy storage element Cf1, D represents a duty cycle (e.g., a ratio ofa conduction time of transistor Q21 to the switching period) oftransistor Q21, Vci1 represents a voltage across energy storage elementCi1, Vcf2 represents a voltage across energy storage element Cf2,Vci(N−1) represents a voltage across energy storage element Ci(N−1),VciN represents a voltage across energy storage element CiN, and Voutrepresents an output voltage. It can be seen from the connectionrelationship shown in FIG. 6 that a voltage across energy storageelement Cfj may be equal to a voltage across energy storage element Cij(e.g., Vcfj=Vcij). Therefore, a relationship between the input voltageand the output voltage of the power converter may be expressed as thefollowing formula (24).

$\begin{matrix}{\frac{Vout}{Vin} = \frac{D}{N}} & (24)\end{matrix}$

In this particular example, due to the interleaving connection and thephase-shift control, the ripple of the output voltage can be reduced,and the required output capacitance of output capacitor Co can also bereduced. Further, the power converter may have a relatively high gainand an adjustable stabilized output voltage. An increased number of theA-type switching power stage circuits can correspond to the low rippleof the output voltage and a high gain, thereby requiring a relativelysmall output capacitance.

Referring now to FIG. 7, shown is a schematic block diagram of a fourthexample power converter, in accordance with embodiments of the presentinvention. In this particular example, the power converter is a Boostpower stage converter. The power converter can include A-type switchingpower stage circuit 71, B-type switching power stage circuit 72,terminal o2, terminal m2, transistor Q71, energy storage element Ci7,and output capacitor Co. Terminal o2 may be configured as an outputterminal of the power converter to generate output voltage Vout, andterminal m2 may be configured as an input terminal of the powerconverter to receive input voltage Vin. A-type switching power stagecircuit 71 can include transistor Q72, energy storage element Cf7,transistor Q73, and magnetic element L71. B-type switching power stagecircuit 72 can include transistor Q74, transistor Q75, and magneticelement L72. For example, each of transistors Q73 and Q75 is arectification switch (e.g., a MOSFET, a BJT, and IGBT, etc.). In anotherembodiment, each of transistors Q73 and Q75 may be replaced with adiode. Energy storage parameters of energy storage elements Cf7 and Ci7may be set to control A-type switching power stage circuit 71 to meetinductor volt-second balance (e.g., to control magnetic element L71 tobe in a stable state). That is, the amount of change in a current ofmagnetic element L71 during a switching period may be controlled to beapproximately zero.

For example, the power converter can perform in-phase control onoperation states of A-type switching power stage circuit 71 and B-typeswitching power stage circuit 72. Under the in-phase control, transistorQ72 may have a same switching state as transistor Q74, and transistorQ71 may have a same switching state as transistor Q73, where theswitching state of transistor Q72 is complementary to the switchingstate of transistor Q73. Transistors Q72 and Q74 may have a same dutycycle D. In this case, the power converter can adjust the duty cycle D,to adjust output voltage Vout and keep stabilization of output voltageVout. Based on characteristics of the inductor volt-second balance ofthe A-type switching power stage circuit and the B-type switching powerstage circuit, the following relationships of formulas (25) and (26) maybe obtained.

Vin=(1−D)*(Vout−Vcf7)  (25)

Vin=(1−D)*Vci7  (26)

Here, Vin represents an input voltage, Vcf7 represents a voltage acrossenergy storage element Cf7, D represents a duty cycle (e.g., a ratio ofa conduction time length of transistor Q72 to the switching period) oftransistor Q72, Vci7 represents a voltage across energy storage elementCi7, and Vout represents an output voltage. It can be seen from theconnection relationship shown in FIG. 7 that the voltage across energystorage element Cf7 may be equal to the voltage across energy storageelement Ci7 (e.g., Vcf7=Vci7). Therefore, a relationship between theinput voltage and the output voltage of the power converter may beexpressed as the following formula (27).

$\begin{matrix}{\frac{Vout}{Vin} = \frac{2}{1 - D}} & (27)\end{matrix}$

In this particular example, due to the interleaving connection and thein-phase control, the power converter may have a relatively high gainand an adjustable stabilized output voltage, and with a relativelysimple control manner. In another example, the power converter mayperform phase-shift control on operation states of A-type switchingpower stage circuit 71 and B-type switching power stage circuit 72.Under the phase-shift control, transistors Q72 and Q74 can be controlledto have a phase difference α (e.g., α is 180°) between conductiontimings of transistors Q72 and Q74. A switching state of transistor Q72may be complementary to a switching state of transistor Q73, a switchingstate of transistor Q71 may be the same as the switching state oftransistor Q73, and a switching state of transistor Q74 may becomplementary to a switching state of transistor Q75. Transistors Q72and Q74 may have a same duty cycle D. In this case, the power convertercan adjust the duty cycle D, in order to adjust output voltage Vout andkeep stabilization of output voltage Vout.

In this particular example, due to the interleaving connection and thephase-shift control, the ripple of the output voltage can be reduced,and the required output capacitance of output capacitor Co can also bereduced. Further, the power converter may have a relatively high gainand an adjustable stabilized output voltage. It should be understoodthat the power converter may include N A-type switching power stagecircuits, one B-type switching power stage circuit, and N “second”energy storage elements. Based on characteristics of the inductorvolt-second balance of the A-type switching power stage circuit and theB-type switching power stage circuit and the above description, arelationship between the input voltage and the output voltage of thepower converter may be obtained as below in formula (28).

$\begin{matrix}{\frac{Vout}{Vin} = \frac{N}{1 - D}} & (28)\end{matrix}$

In this particular example, due to the interleaving connection and thephase-shift control, the ripple of the output voltage can be reduced,and the required output capacitance of output capacitor Co can also bereduced. Further, the power converter may have a relatively high gainand an adjustable stabilized output voltage. An increased number of theA-type switching power stage circuits can correspond to the low rippleof the output voltage and a high gain, thereby requiring a small outputcapacitance.

Referring now to FIG. 8, shown is a schematic block diagram of a fifthexample power converter, in accordance with embodiments of the presentinvention. In this particular example, the power converter can includeone A-type switching power stage circuit and one B-type switching powerstage circuit. In this particular example, magnetic elements L81 and L82can be coupled with each other, while the ripple of the output voltageand the required output capacitance of output capacitor Co can befurther reduced.

Referring now to FIG. 9, shown is a schematic block diagram of a sixthexample power converter, in accordance with embodiments of the presentinvention. In this particular example, the power converter can includetwo A-type switching power stage circuits and one B-type switching powerstage circuit. In this particular example, magnetic elements L91 and L92can be coupled with each other, while the ripple of the output voltagecan be further reduced and the required output capacitance of outputcapacitor Co can also be further reduced. In particular embodiments, thepower converter can include N A-type switching power stage circuits andone B-type switching power stage circuit. At least one of magneticelements L91 and L93 can be coupled with magnetic element L92, or atleast two of magnetic elements L91 and L93 can be coupled with eachother. In this way, the ripple of the output voltage and the requiredoutput capacitance can be further reduced.

The embodiments were chosen and described in order to best explain theprinciples of the invention and its practical applications, to therebyenable others skilled in the art to best utilize the invention andvarious embodiments with modifications as are suited to particularuse(s) contemplated. It is intended that the scope of the invention bedefined by the claims appended hereto and their equivalents.

What is claimed is:
 1. A power converter, comprising: a) a firstterminal; b) a second terminal; c) N A-type switching power stagecircuits, each having a first energy storage element, wherein N is apositive integer, wherein a first terminal of a first A-type switchingpower stage circuit in the N A-type switching power stage circuits iscoupled to the first terminal of the power converter, and a secondterminal of each of the N A-type switching power stage circuits iscoupled to the second terminal of the power converter; d) one B-typeswitching power stage circuit; and e) N second energy storage elements,wherein each of the N second energy storage elements is coupled to oneof the N A-type switching power stage circuits, and wherein the B-typeswitching power stage circuit is coupled between a terminal of one ofthe N second energy storage elements corresponding to the B-typeswitching power stage circuit and the second terminal of the powerconverter.
 2. The power converter of claim 1, wherein energy storageparameters of first energy storage elements of the N A-type switchingpower stage circuits and the N second energy storage elements areconfigured to control the N A-type switching power stage circuits tomeet inductor volt-second balance.
 3. The power converter of claim 1,wherein when N is greater than 1, an n-th A-type switching power stagecircuit from the N A-type switching power stage circuits is coupledbetween a terminal of an (n−1)-th second energy storage element amongthe N second energy storage elements and the second terminal of thepower converter, and a j-th second energy storage element from the Nsecond energy storage elements is coupled between a j-th A-typeswitching power stage circuit among the N A-type switching power stagecircuits, and a ground, wherein n is a positive integer of at least two,and is a positive integer.
 4. The power converter of claim 1, furthercomprising N first transistors, wherein each of the N second energystorage elements is coupled to the A-type switching power stage circuitcorresponding to the second energy storage element via one of the Nfirst transistors connected in series with the second energy storageelement.
 5. The power converter of claim 4, wherein each of the N A-typeswitching power stage circuits further comprises a second transistorcoupled between a first terminal of the A-type switching power stagecircuit and the first energy storage element.
 6. The power converter ofclaim 5, wherein each of the N A-type switching power stage circuitsfurther comprises: a) a third transistor coupled between the firstenergy storage element and ground; and b) a first magnetic elementconnected between the first energy storage element and the secondterminal of the power converter.
 7. The power converter of claim 6,wherein the B-type switching power stage circuit comprises: a) fourthand fifth transistors coupled between the second energy storage elementcorresponding to the B-type switching power stage circuit and ground;and b) a second magnetic element coupled between the second terminal ofthe power converter and a common node between the fourth and fifthtransistors.
 8. The power converter of claim 1, wherein: a) the firstterminal of the power converter is configured as an input terminal ofthe power converter to receive an input voltage; and b) the secondterminal of the power converter is configured as an output terminal ofthe power converter to generate an output voltage.
 9. The powerconverter of claim 1, wherein: a) the second terminal of the powerconverter is configured as an input terminal of the power converter toreceive an input voltage; and b) the first terminal of the powerconverter is configured as an output terminal of the power converter togenerate an output voltage.
 10. The power converter of claim 7, whereinphase-shift control is performed on operation states of the N A-typeswitching power stage circuits and the B-type switching power stagecircuit.
 11. The power converter of claim 10, wherein: a) the secondtransistor of each of the N A-type switching power stage circuits has asame duty cycle as the fourth transistor; b) a switching state of thesecond transistor is complementary to a switching state of the thirdtransistor; c) a switching state of the fourth transistor iscomplementary to a switching state of the fifth transistor; d) aswitching state of a j-th first transistor from the N first transistorsis complementary to a switching state of a third transistor of a j-thA-type switching power stage circuit from the N A-type switching powerstage circuits, wherein j is a positive integer; and e) the powerconverter is configured to adjust the duty cycle of the secondtransistor to generate a stabilized output voltage.
 12. The powerconverter of claim 11, wherein when N is greater than 1, there is a samephase difference between conduction timings of adjacent secondtransistors among the N second transistors, and the same phasedifference between a conduction timing of an N-th second transistoramong the N second transistors and a conduction timing of the fourthtransistor.
 13. The power converter of claim 12, wherein the phasedifference is 360°/(N+1).
 14. The power converter of claim 7, whereinin-phase control is performed on operation states of the N A-typeswitching power stage circuits and the B-type switching power stagecircuit.
 15. The power converter of claim 14, wherein: a) the secondtransistor of each of the N A-type switching power stage circuits has asame switching state as the fourth transistor; b) the third transistorof each of the N A-type switching power stage circuits has a sameswitching state as the N first transistors and the fifth transistor, andthe switching state of the third transistor is complementary to aswitching state of the second transistor; and c) the power converter isconfigured to adjusting a duty cycle of the second transistor togenerate a stabilized output voltage.
 16. The power converter of claim7, wherein each of the third and fifth transistors comprises arectification switch.
 17. The power converter of claim 7, wherein eachof the third and fifth transistors comprises a diode.
 18. The powerconverter of claim 7, wherein: a) at least one of first magneticelements of the N A-type switching power stage circuits is coupled withthe second magnetic element; and b) at least two of first magneticelements of the N A-type switching power stage circuits are coupled witheach other.
 19. The power converter of claim 7, wherein at least one offirst magnetic elements of the N A-type switching power stage circuitsis coupled with the second magnetic element.
 20. The power converter ofclaim 7, wherein at least two of first magnetic elements of the N A-typeswitching power stage circuits are coupled with each other.